Background
The aircraft was a single-engine airplane conducting a non-scheduled charter flight from High Lake to Desolation Lake. The flight departed High Lake at 1745 local time with a pilot and three geologists aboard.
Accident
The aircraft failed to arrive at Desolation Lake and was reported missing later that same day. The wreckage was discovered on 30 August approximately 2 miles south of High Lake. The aircraft was destroyed, and all four occupants were killed.
Investigation
Examination of the wreckage revealed the presence of water in the fuel lines, screens, and filters in quantities sufficient to cause engine failure. The aircraft had attempted a forced landing but struck the ground at a steep angle, estimated at approximately 60 degrees from the horizontal, indicating that the aircraft was out of control at impact.
Probable Cause
The official probable cause of the accident was loss of control resulting from engine failure. The engine failure was caused by water contamination in the fuel system.